This invention relates to a filter for removal of particulate matter from an air stream. More particularly, the invention relates to a self-cleaning filter.
In various types of equipment there is frequently generated a gas stream laden with dust and particulate matter. In a grain dryer, for example, warm air circulating through the grain entrains particles which might then be discharged to the atmosphere. Recent emphasis on environmental quality, however, has prompted the search for new and improved air polution control methods. One technique for efficiently controlling air pollution to which this invention particularly relates has been the separation of unwanted particulate matter from a gas stream by a filter media. A filter screen is typically placed in the gas stream exhaust and dust simply collects on the filter surface as the gas passes through the filter.
To permit continuous operation of the equipment, it is known to provide a vacuum sweep arm which travels over the filter surface and removes the collected material. An example of such equipment is shown in my earlier U.S. Pat. No. 3,377,780, issued Apr. 16, 1968 and entitled "Self-Cleaning Filter Apparatus". Equipment of this genre includes a circular filter screen placed in the exhaust gas stream with a centrally supported vacuum sweep arm which angularly rotates about the center of the filter to continuously clean the surface. Although generally effective in its cleaning function, this equipment has not been without drawbacks.
Heretofore it has been necessary, for example, to maintain the filter surface in a rigid and perfectly flat plane in order to insure effective cleaning of the surface since the vacuum arm rotates in a flat plane. Should the filter become warped in any way, the vacuum arm cannot maintain contact with the warped section and only partial cleaning results. Thus significant attention is devoted to provide extensive structural support to maintain a perfectly flat filter surface. Similarly, adjustments to, and support of, the vacuum arm are critical to insure appropriate contact of the cleaning head with the filter surface.
Needless to say, the structural framework, supports and bracing needed for these considerations are costly additions to the equipment. Such structural details are reflected in two other areas in addition to cost. First, shipping of the filter apparatus to the job site is a handicap. Because of the critical relationship between the vacuum arm and the filter surface, the filter apparatus is normally preassembled by the manufacturer and then shipped as a single unit, albeit a bulky and cumbersome one, for installation. Secondly, space limitations on the filter equipment may be imposed by the dimensions and configurations of the grain dryer or other equipment on which the filter is to be installed. Accordingly, it is easily seen that some applications are severly limited by the size of the filter apparatus. The framework and structural components have of course been the chief contributors to the significant size of such equipment.
The primary goal of this invention is to provide a self-cleaning filter of reliable construction, possessing superior characteristics of operation and manufacture, and which is free of the limitations and drawbacks of filters heretofore found in the industry.
More particularly, an object of the invention is to provide a self-cleaning filter with emphasis on economy. Excess structural components are eliminated to reduce both the manufacturing cost and size of the equipment. As a corollary advantage, the filter may be employed in a broader spectrum of applications where size of the filter apparatus must be maintained at a minimum.
Another object of the invention is to provide a self-cleaning filter apparatus which may be shipped to the job site in a disassembled condition to minimize both bulk and expense. Thereafter, the equipment may be easily installed in the exhaust gas stream of the plant.
An additional object of the invention is to provide a self-cleaning filter which relies upon the structural integrity of the grain dryer or associated equipment for support of the filter surface. Thus is eliminated the necessity for an elaborate support and bracing system commonly associated with filter apparatus of this type.
A further object of the invention is to provide a self-cleaning filter wherein the filter surface need not be maintained in a rigid, flat plane to insure effective cleaning. Herein provided is a vacuum rotor arm with a cleaning head especially adapted to sweep an undulating or warped surface to remove particulate matter collected thereon.
Yet another object of the invention is to provide a self-cleaning filter of the character described which may be fabricated in a variety of sizes without requisite changes in the drive and vacuum connections. In other words, dimensional changes are demanded only for the filter itself and the associated vacuum arm when a size change is required.